More from WebMD

Sept. 26, 2011 -- Children who have diabetes may be more likely to also have asthma. What's more, kids with both conditions are more likely to have poor control over their diabetes.

These are the two main findings of a new study in Pediatrics.

The study didn't explore why asthma and diabetes may be linked. But the two conditions share certain risk factors, including obesity.

They are also both related to underlying inflammation, says study researcher Mary Helen Black, PhD. She is a biostatistician/data consultant at Southern California Permanente Medical Group in Pasadena.

Black says that the next step will be to look at how diabetes and asthma are connected.

"Having to deal with diabetes all by itself is very difficult, so other things may go unnoticed or unchecked and it is important for physicians and parents to be mindful of a potential connection," she says.

Comparing Asthma Rates

The new study looked at asthma rates from 2002 to 2005 for 1,683 kids with type 1 diabetes and another 311 who had type 2 diabetes. Close to 11% of these children also had asthma, the study showed. This number is higher than the 8.7% seen among all children in the U.S.

Among children with diabetes who had asthma, the rate was higher in children who had type 2 diabetes. The asthma rate for those children was 16.1%, vs. 10% for children with type 1 diabetes. Many children in the study with either type of diabetes were overweight or obese.

Those children with asthma and diabetes had higher levels of hemoglobin A1c (HbA1c). This blood test provides a snapshot of average blood sugar control for the past two to three months. Poor blood sugar control is linked to many of the complications associated with diabetes.

"Among youth with diabetes, those with asthma were more likely to fall into the category of poor glucose control," Black says.

Medication and Blood Sugar Control

Children whose asthma was not treated with medication were more likely to have poor control of blood sugar than those with treated asthma.

The researchers suggest that certain asthma medications such as leukotrieneinhibitors may improve blood sugar control among children with asthma and diabetes. Other asthma medications such as oral steroids are known to sometimes increase blood sugar.

Harold Farber, MD, urges caution in interpreting the new study. Farber is a pediatric pulmonologist at Texas Children's Hospital in Houston.

"It is provocative, but we need more research," he says. Farber is also a professor of pediatrics - pulmonary at Baylor College of Medicine.

The study does bring some reassuring news, he says. "We worry that some asthma medications cause problems with diabetes control. And while this study was not designed to test that, it seems that not taking your asthma medications was more of a problem than controlling your asthma."

"Taking good care of asthma also bodes well for diabetes," he says.

This is a good thing, says Janine Sanchez, MD. She is an associate professor in the division of pediatric endocrinology, University of Miami Miller School of Medicine.

"Kids with asthma have worse diabetes control if they are not taking care of asthma," she says. "Both medical conditions should be treated."